Relay mounting



Dec. 2, 1958 F. A. ZUPA RELAY MOUNTING Filed Nov. 27, 1953 FIG.

lNl/ENTOR F. A. ZUPA fwd/ 44.

ATTORNEY United States Patent Q RELAY MOUNTING I Frank A. Zupa, New York, N. Y., assignor to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application November 27, 1953, Serial No. 394,818

7 Claims. (Cl. 317165) Rack-mounted relays are normally supported by means of a core extension which is attached to a channel or other structural member by means of machine screws or other similar fastening devices. It has been found that this method of attachment frequently distorts the core and inevitably produces substantial internal stresses in the core assembly structure. Consequently, a relay which has its armature travel and contact positions accurately adjusted during manufacture will frequently become maladjusted during mounting; and a relay accurately adjusted after mounting will tend to lose its adjustment with the shifts of core position which occur as a result of the gradual relieving of the aforesaid internal stresses, this loss of adjustment tending to be accelerated by subsequent handling of the relay and by movement of the equipment of which the relay is a part.

Additionally, it is now recognized that a rack-mounted relay, when pulsed, will tend to oscillate since the core, regardless of its apparent rigidity, actually acts as a flexible member. At critical pulse frequencies, the amplitude of the movement of the free end of the cantilevermounted core has been found to be very substantial. Obviously, these oscillations result in instantaneous variations in the dynamic relations between the relay parts so that even though the relay be in proper adjustment when unoperated and idle, it may not so be when the relay has just restored to its unoperated position following pulsing. It is also apparent that the oscillation of the core will tend to accelerate the aforesaid shifting of the static position of the core due to changes in the internal stress conditions of the core structure.

While these factors serve to render any rack-mounted relay maladjusted, the condition is particularly severe with highly sensitive relays because adjustment of those relays is necessarily more critical and the structure per se is normally less massive, less rigid and more subject to distortion.

Since the expense of repetitively readjusting relays can become substantial, various efforts have been made to reduce the tendency toward maladjustment. These efforts have been directed both towards more rapidly and more flexibly attaching a relay to its supporting channel, but normally, regardless of the presence or absence of an interposed support detail, the core structure has been rendered integral with the supporting channel. Further, it has not generally been perceived that it is imperative that the position of the front end of the core be closely controlled both statically and dynamically if a relay is to retain its adjusted condition, nor has there been recognition of the fact that this control must be exercised without imposing additional static stresses in the internal structure of the core.

Therefore, under the precepts of the present invention a sensitive relay is provided with a cover which cover constitutes the primary medium of support for the relay. The cover is mounted on the supporting channel, the rear end of the relay is semifiexibly attached to the cover and the front end of the core is restricted in its movement to a limited amplitude of oscillation, but being free, within those limitations, to assume an unrestrained static position.

The exact nature of this contribution to the art may be more fully understood from the following detailed description of one embodiment of the invention when read with reference to the accompanying drawings in which:

Fig. 1 is a plan or top view of a covered, sensitive relay mounted in accordance with the principles of the invention, with part of the cover and part of the coil being cut away for purposes of clarity;

Fig. 2 is a view taken from the rear end of the relay shown in Fig. l with a portion of the cover structure being cut away; and

Fig. 3 is a view taken from the front end of the relay shown in Fig. 1 with the front cover removed.

The relay shown in the drawings is, except for certain modifications hereinafter to be described, a conventional type well known in the art. It is characterized primarily as a highly sensitive relay, being operable on very small currents. As a result, adjustment of the relay is critical and must be accurately maintained.

In general, the relay comprises a core 1 which is a long flat member extending through and rearwardly of the coil 2 and terminating at the rear of the relay, in an enlarged core crosspiece 3. The cross-section area of the core 1 is normally small in view of the magnetic and inductance requirements of sensitive relays. The core crosspiece 3 serves as the fundamental structural element of the relay, and supports the armature 4 through the medium of the armature spring 5, and supports the contact spring pile-up assembly represented generally at 6. Formerly, this core crosspiece 3 bore certain extensions which were apertured and tapped to receive machine screws to mount the relay to the support channel. This method of support, however, has been found to tend to distort the core and to establish internal stresses in the core structure, as before noted.

Extending forwardly of the relay and in spaced relation to the core is a plurality of spring members 7, at least some of which bear electrical contacts engageable with contacts on the armature 4. The initial spacing between the contacts carried by the members 7 and the contacts on the armature 4 may be controlled and adjusted by means of the adjusting screws 8 threaded into the bushings 25, which are secured in suitable orifices in the ears 26 of the spoolhead or end member 27. For present purposes, these screws and bushings may be any suitable type, but preferred forms of them are shown in Fig. 1 of the drawings and are further disclosed and claimed in Patent 2,802,503, issued August 13, 1957, on my copending application, Serial No. 394,819, filed November 27, 1953.

Sensitive relays of this type have normally been provided with iron covers to minimize disturbances from adjacent magnetic fields and to prevent malfunctioning due to dust. It has previously been the practice to mount the relay to the supporting channel, in the previously described fashion, and then to mount the cover to the relay. In the disclosed embodiment of the invention a rectangular parallelepiped main cover 10 which is open both at portion 16 of the'support bracket.

the front and the rear is provided. A front cover 11 is removably afiixed'to the main cover to enclose the front of the relay. Extending across the open rear end of. the cover 1!) is a mountingbracketlll, (Figs. land 2) which is weldedor otherwiseafiixedtothe cover. Mounting holes 13 are provided in the bracketll for assembling thecover to the support channel or other structural member 14 on the relay mounting. rack.

To support the relay withinthe cover, a support bracket is'provided'which includes a cross member 315 (Fig. 2) secured to the core crosspiece.3 by means, for example, of screws engaging a spacing strip 19 and the support bracket cross member 1'5. At each side of the relay, the supportbracketis in the shape of a U, having a first portionor leg 16, integral with the cross member 1'5, extending laterally of therelay, a second portion or bridging member 17" extending longitudinally of the relay and a third portion'orleg 18 extending. laterally of the relay andin approximate parallelism with the aforesaid first Each of the legs 18 is suitably apertured and preferably tapped so as to be attachable to the cover 10 by means of screws 20 (Fig. 2). Portions 17 areformed with an offset (Fig. 1) so that themain cover 10 will clear the portions 18 during assembly. When the screws 20"are tightened, the portions 1? flex to permit the portions 18 to move into engagement With-the cover. By virtue of this configuration and through the appropriate selection of materials, the support brackets are less rigid than the core structure by a substantial factor. Therefore, if when assembling the relay within the cover structure by means of screws 20, the fit is not exactso that some element or elements of the-overall structure are distorted as the screws 20 are tightened, the distortion will occur either in the cover MB or in the support bracket and not in the-core-or armature structures. It is of course'clear that the core will not be distorted as a result of the affixing of' the cover to. any supporting channel.

As before noted, a relay when mounted on a rack will tend to.oscillate as a. unit and this condition is particularly critical Where a relay must operate under pulsing conditions. In order that there be maximum stability of adjustment of the relay, it is important that the front endof the core ll: be accurately positioned initially and thatit be maintained in that position. But if any force, however slight, beexerted to restrain the motionof the core or to, displace it from its free position, there will be internal, stresses, set up in the core structure which will ultimately result in maladjustment of the relay. It has been found, therefore, that means must be provided to limit the motion of the, core without in anyway restricting its assumption of a free andunrestrained initial or idle position. Any means,,regardless of its resiliency, which engages the forward end of thecorewhen the relay is idle will not meet this requirement and, as a consequence, springs and rubber cushions. have been found to be unsatisfactory. A suitable means, obviating the difficulties and meeting the requirements, isthe amplitude limiting bracket 22 which may beseen most clearly in Figs. 1 and 3 of the drawings. Bracket 22 comprises a first portion in juxtaposition with the cover 10 and affixed thereto by meansofscrews 23. Another portion of the amplitude limiting bracket22extends perpendicularly to the above-mentioned firstportion and perpendicularly to the longitudinal axis of the core. portion of bracket: 22 isprovidedwith an, aperture 24 which is wider than the front end of the core 1 so that the edges defining the aperture 24 will normally lie in spaced proximity to thecorel. The relay is preferably so designed and the tolerances-so specified that the, front end of the core lwill becentered in the-aperture 24. It is desirable that the core 1; bespaced fromthe edges defining the opening 24 whenthe relay .is initially assembled to .insure that there are-noforcesacting upon the front end of core 1.to in any way distort it from its free or idle This latter position. However, since the edges of the aperture 24 are in proximity to the core 1, they impose a limit upon the amplitude of oscillation or vibration of the front end of the core 1. As one example, it has been found that with the front end of the core 1 being in the order of .078 inch thick and .437 inch wide, the aperture 24 should be in the order of .088 inch wide and .447 inch long.

Therefore, the relay may be mounted, via the cover it, to a supporting channel without any distortion of the core resulting from the attachment since the rear end of the relay is supported by means which are more flexible than the core structure itself, and the front end of the core may be accurately limited in its motion with out any restraints whatsoever: being imposed upon the free, idle position of that end. In this manner, the relay is mounted so that it will maintain its critical adjustment for greatly extended. periods.

It istobe understood, that the above-described arrangements are but illustrative of the application of the principles of the invention. Numerous other arrangements may be devised by those skilled'in the art without departing fromthe spirit, and, scope of the invention.

What is claimed is:

1. In combination with a mounting channel and a relay having a core, a cover for said relay, means for aflixing said cover to said mounting channel, a support bracket affixed'to each side of said relay at one end thereof and affixed to said cover, and an amplitude limiting bracket affixed to said coverv and loosely engaging said relay at the. other end" thereof;

2; Incombination with a mounting channel and a relay having a core, a cover enclosing said relay, a mounting bracket integral with the rear end of said cover, means for aflixing said mounting bracket to said mounting channel,a support bracket aflixedto each side of said relay at one' end'thereof and'aifixed to. said cover, and an ampli tude limiting bracketiaffixed to said cover and loosely engaging said relay at the other end thereof.

3. In combination with a mounting channel and a relay having a core, a cover for-said relay, means for affixing said cover to said'mounting channel, a pair of support brackets integral with the rear end of said core andextending-forwardly and then laterally on each side of said relay, means for afiixing the said laterally extending portions of said support brackets to said cover, and an amplitude limiting bracket affixed to said cover and loosely engaging the front end of said core.

4. In combination with a mounting channel and a relay having a core, a cover for said relay, means for affixing said cover to said mounting channel, a support bracket afiixed toeach side of said relay at one end thereof and afiixed' to said cover'adjacent said sides and intermediate said one end and other end, and an amplitude limiting bracket having a first portion affixed to said cover and a second'portion extending perpendicularly to said core and having an aperture therein, the sides forming said aperture normally lying in spaced'proximity to said core thereby to limit the amplitude of motion of said core.

5. In combination with a mounting channel and a relay having a: core, acover enclosing said relay, a mounting bracketiextending across the rear end of said cover, means for afiixing said mounting bracket to said mounting channel, a; pair of-support" brackets integral with the rear end of saidcoreand extending forwardly and thenlaterally on eachzside. of said relay, means for afiixing the said laterally extending portions of said support brackets to said cover,v and anamplitude limiting bracket having a first portion aflixed to said cover and asecondportion extending. perpendicularly to the center line of said core and havinganaperture therein, the. sides forming said aperture normally lyingin spaced proximity to said core thereby toalimitthe amplitude of motion of said'core.

6... Stress reducing support means associated with a sensitive electromagnetic relay-which is encased in a cover having an integral mounting bracket and which comprises a thin fiat core, a coil and an armature cooperating with said core, and a plurality of contact springs having cooperating contact surfaces capable of accurate adjustment and selectively actuable by the movement of said armature, said stress reducing support means comprising a support bracket integral with the rear end of said core and having a pair of forwardly extending portions disposed along each side of said relay in planes essentially parallel to the longitudinal axis of said core, said portions having laterally extending projections thereon to couple said relay to said cover, and an amplitude limiting bracket having one of its legs afiixed to said cover and having its other leg extending in a plane substantially perpendicular to said longitudinal axis of said core and apertured such that the edges defining said aperture loosely surround the forward end of said core to limit the amplitude of motion of said core.

7. Stress reducing support means associated with a sensitive electromagnetic relay which is encased in a cover having an integral mounting bracket and which comprises a thin fiat core, a coil and an armature cooperating with said core, and a plurality of contact springs having cooperating contact surfaces capable of accurate adjustment and selectively actuable by the movement of said armature, said stress reducing support means comprising a unitary bracket having a fiat portion fixedly attached to the rear end of said core and a pair of forwardly extending U-shaped portions disposed along each side of said relay with the legs thereof lying in planes essentially perpendicular to the plane of the flat surfaces of said core and parallel to the longitudinal axis of said core, the forwardmost legs of said U-shaped portions 0&- set slightly in an outward direction from the planes of said U-shaped portions generally in order to couple said relay to said cover by virtue of said forwardmost legs only, and an amplitude limiting L-shaped bracket having one leg affixed to said cover and having its other leg extending in a plane substantially perpendicular to said longitudinal axis of said core and apertured rectangularly whereby the sides of said aperture loosely surround the forward end of said core to limit the amplitude of motion of said core,

References Cited in the file of this patent UNITED STATES PATENTS 847,555 Craft Mar. 19, 1907 2,115,804 Fondiller May 3, 1938 2,115,836 Zupa May 3, 1938 2,190,685 Slater Feb. 20, 1940 2,274,296 Hughes Feb. 24, 1942 2,565,697 Odstrcil Aug. 28, 1951 

